OPTIMIZATION OF TURBOCHARGER PORTED SHROUD COMPRESSOR STAGES

With increasing low-end torque and high-power requirements, passenger vehicle applications need large map-width compressor-stages at high-pressure ratio (3.0 and above). Compressor stages in which wheels operate in a normal housing exhibit limitations in stability at high-pressure ratio and in maximal flow capacity. The application of a ported shroud typically improves the surge characteristics of a centrifugal compressor In this paper an optimisation procedure for ported-shroud compressor stages was developed based on Design Of Experiment (DOE) procedure. Two DOE procedures are used. The first one is used to optimize the port location, wheel exducer width and diffuser width; the second is used to optimise the housing volute throat area, diffuser width and diffuser outlet radius. The compressor-stage performance was obtained by using a commercial CFD package. After the first DOE, an experimental DOE with a reduced design space was carried out to obtain the optimised port location and wheel exducer width. After the second DOE and optimization, only most promising configurations were manufactured for tests. The DOEs' procedures and results as well as the CFD results are discussed and analyzed in the paper Finally, the relative difference between the CFD and tests are discussed. In comparison to the baseline ported-shroud housing, the final configuration has improved map width by 9%, an increased pressure ratio by 0.2 and a higher peak efficiency by about1 point.